A tissue ablator is a device used to cauterize, or induce necrosis of, living tissue. Intrauterine tissue ablators are useful for treating menorrhagia and metrorrhagia, excessive bleeding conditions sometimes evidenced by pain or discomfort.
Ablation is usually accomplished by thermal or cryogenic treatments. One thermal procedure involves treatment of the tissue with a laser or electrocautery device. A physician using this procedure for uterine ablation must "paint" the intrauterine surface with the laser beam or electrocautery probe, making it difficult to uniformly treat the entire intrauterine area. Incomplete treatment results in continued bleeding or discomfort. Also inherent in the laser and electrocautery techniques is the risk that an area of the tissue surface will be punctured from prolonged exposure to the beam or probe.
Another method of organ ablation involves an inflatable bladder which is inserted into the organ and inflated with a thermal or cryogenic substance. The inflated bladder contacts the surrounding tissue and the extreme temperature of the thermal or cryogenic substance in the balloon causes the tissue to necrose.
One such device intended for intrauterine cauterization is disclosed in U.S. Pat. No. 4,949,718. An inflatable bladder located at the end of a cannula is inserted into the uterus. A liquid medium is used to fill the bladder, causing it to inflate inside the organ. Heating coils located inside the bladder heat the medium to temperatures of 1900.degree. to 215.degree. F., temperatures known to induce necrosis of endometrial tissue. The temperature of the medium is maintained until the tissue surfaces in contact with the bladder are cauterized. U.S. Pat. No. 5,105,808 describes an intrauterine cauterizing method utilizing the device just described.
This device suffers from several disadvantages. Firstly, the bladder used is substantially spherical, whereas the uterus is bicornuate in shape. The cornual regions of the uterus therefore remain untreated because the spherical bladder does not make contact with them (see FIG. 1). Moreover, the device does not allow the physician to visually verify that the bladder has been properly placed or that the entire endometrial surface has been sufficiently cauterized. The patient may continue to suffer bleeding or discomfort as a result of incomplete cauterization. Finally, the heating element is located inside the body during treatment. The heating coil reaches temperatures much higher than the fluid temperature and its placement in the bladder creates the risk that the patient may be burned.